Three approaches may be used to provide proximity-based service nowadays: direct communications, local switching and network-assisted direct communications. Generally speaking, in the direct communication approach, the two parties communicate directly to each other, in which the two devices discover each other and establish a communication link. For the local switching approach, the two parties may communicate through a base station (BS), and in this case, device to device (D2D) communicate through the BS. On the other hand, in network-assisted direct communications, one party communicates with the other through the assistance from a BS. Therefore, the BS assists a device to discover the other device and the two devices establish direct communications.
However, direct communications may be ineffective in providing information which is of interest to the users. Such a user may not be within the coverage area of a point of interests, and the user may not notice another user in proximity.